The present invention relates generally to a semiconductor integrated circuit device and a manufacturing technique thereof and, more specifically, it relates to a semiconductor integrated circuit device including a structural portion formed by stacking a chalcogenide film on a conductive plug, as well as a technique which is effectively applied to the manufacture thereof.
Semiconductor memories include a volatile DRAM (Dynamic Random Access Memory) and a non-volatile memory semiconductor integrated circuit device such as a flash memory. An increase in the integration degree for each of the memories requires miniaturization of a memory device (cell) and the technology node (technical generation of design dimension) is going to reach the order of 0.2 to 0.1 μm. Then, along with the increased miniaturization, the amount of storage that can be retained in the cell, for example, the amount of charges accumulated in a DRAM capacitor cell is abruptly decreased. Therefore, the intensity of taken out signals is lowered making it difficult to judge the memory state between 1 and 0. As a countermeasure, technical development has been conducted, for example complication of the cell capacitor structure (provision of unevenness or the like) or tantalum oxide having high dielectric constant and put to practical use. However, the technology node for the next generation has come to a limit only by the complication of the cell or application of high dielectric film along with miniaturization. In the flash memory as the non-volatile memory, since the structure is simple, the cell structure is not so complicated as in the DRAM. However, the film thickness of the tunnel insulative film for retaining charges has been reduced to several nanometer along with miniaturization and control of the film property has resulted in a significant subject. Further, the flash memory has a drawback in that the rewriting rate of storage is lower compared with the DRAM. Under the technical background described above, there has been an increasing expectation for a semiconductor integrated circuit device mounting a new memory that is non-volatile and has a simple structure.
As a new memory semiconductor integrated circuit device capable of satisfying such a demand, development has been progressed for the technique of a semiconductor integrated circuit device using, as a memory device, a chalcogenide film (film comprising an element belonging to group VIb such as tellurium as a main ingredient) used in a DVD (Digital Versatile Disk) as an optical writing recording medium. The memory device provides memory information by utilizing a difference in the resistance by from 1 to 3 digits between the amorphous state and the crystalline state of the film. Unlike the DVD, in the memory device, the film is made crystalline or amorphous by utilizing the Joule heat generated by a pulse current. Since the phase change as described above is utilized, it is referred to as a phase change memory. It can be said that the memory is now under the process of technical development, and an alloy film of germanium (Ge), antimony (Sb) and tellurium (Te) is used as the chalcogenide material (hereinafter the alloy film is referred to as GST film). Such a phase change memory is described, for example, in U.S. Pat. No. 5,166,758 (Patent Document 1), Stefan Lai, et al. “IEEE IEDM Tech. Dig.”, p. 803-806, 2001 (Non-Patent Document 1), or Y. C. Chen, et al. “Proc. IEEE Custom Integrated Circuits Conference” 2003, p. 395-398 (Non-Patent Document 2).
For the manufacture of chalcogenide, examples of the flow rate ratio of nitrogen added to the argon gas are disclosed, for example, in the following documents.
R. Kojima et al, “Jpn. J. Appl. Phys.”, Vol. 37, pp. 2098-2103, 1998 (Non-Patent Document 4) discloses that the addition flow rate ratio of nitrogen added to the argon gas is about 30% to 40%. In T. H. Jeong et al, “Jpn. J. Appl. Phys.”, Vol. 39, pp. 2775-2779, 2000 (Non-Patent Document 5) discloses the same extent of the addition flow rate ratio of nitrogen added to the argon gas. Further, A. Ebina et al, Vac. Sci. Technol. A”, Vol. 17, pp. 3463-3466, 1999 (Non-Patent Document 6) discloses that oxygen is added and the flow rate ratio of the addition gas is about 5% to 10% (Non-Patent Document 6).